Semiconductor substrate, method for manufacturing semiconductor substrate, semiconductor device, and electronic device

ABSTRACT

A single crystal semiconductor layer is formed over a substrate having an insulating surface by the following steps: forming an ion doped layer at a given depth from a surface of a single crystal semiconductor substrate; performing plasma treatment to the surface of the single crystal semiconductor substrate; forming an insulating layer on the single crystal semiconductor substrate to which the plasma treatment is performed; bonding the single crystal semiconductor substrate to the substrate having the insulating surface with an insulating layer interposed therebetween; and separating the single crystal semiconductor substrate using the ion doped layer as a separation surface. As a result, a semiconductor substrate in which a defect in an interface between the single crystal semiconductor layer and the insulating layer is reduced can be provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor substrate, and a methodfor manufacturing a semiconductor substrate, a semiconductor device, andan electronic device.

2. Description of the Related Art

In recent years, an integrated circuit that uses an SOI (silicon oninsulator) substrate replacing a silicon wafer formed by cutting aningot of a single crystal semiconductor into thin slice, has beendeveloped. An SOI substrate has a structure in which a thin singlecrystal silicon layer is provided on an insulating surface. By usingthis structure, a parasitic capacitance between a drain of a transistorand a substrate can be reduced and performance of a semiconductorintegrated circuit can be improved.

There are various methods for manufacturing an SOI substrate; however, aSmart Cut (registered trademark) method is known for achieving both highquality and a high productivity (throughput) of a single crystalsemiconductor layer to be formed. In the Smart Cut method, afterintroducing hydrogen ions into a single crystal silicon substrate (abond wafer), the single crystal silicon substrate is bonded with anothersubstrate (a base wafer) at a room temperature. Bonding is performed byforming strong joining by van der Waals force. After the bonding, thesingle crystal silicon substrate is separated with heat treatment at atemperature of about 500° C., in a region in which the hydrogen ions areintroduced.

As a technical example of forming the single crystal silicon thin filmusing such a Smart Cut method, the one proposed by the present applicantcan be noted (for example, see patent document 1; Published PatentApplication Ser. No. 11-163,363).

In the patent document 1, by forming an insulating film on a glasssubstrate, contamination of a single crystal silicon layer is prevented,and a high-performance semiconductor device is provided.

SUMMARY OF THE INVENTION

However, as for the problems when a single crystal silicon thin film isformed over a glass substrate by using a Smart Cut method, it is notlimited to a problem of contaminant caused by the substrate. As anexample, there is a problem due to damage with ion irradiation. However,since the Smart Cut method requires the ion irradiation, the problem dueto the ion irradiation cannot be avoided.

In view of the above problems, it is an object of the present inventionto provide a semiconductor substrate in which the problem due to the ionirradiation is solved and from which preferable characteristics can beobtained. In addition, it is another object of the present invention toprovide semiconductor devices and electronic devices using thesemiconductor substrate.

In the present invention, plasma treatment is performed to the surfaceof a single crystal semiconductor layer after ion irradiation.Accordingly, contaminant on the surface of the single crystalsemiconductor layer can be removed and the minute surface can be formed.In other words, a defect in an interface between the single crystalsemiconductor layer and an insulating layer to be formed later can bereduced.

A feature of a method for manufacturing a semiconductor substrate of thepresent invention is to include the following steps: forming a damagedregion (also referred to as an ion implanted layer or an ion dopedlayer) at a given depth from a surface of a single crystal semiconductorsubstrate; performing plasma treatment to the surface of the singlecrystal semiconductor substrate; forming an insulating layer on thesurface of the single crystal semiconductor substrate to which theplasma treatment is performed; bonding the single crystal semiconductorsubstrate and a substrate having an insulating surface with theinsulating layer interposed therebetween; performing heat treatment tothe single crystal semiconductor substrate to separate the singlecrystal semiconductor substrate in the damaged region and to form asingle crystal semiconductor layer over the substrate having theinsulating surface.

Another feature of a method for manufacturing a semiconductor substrateof the present invention is to include the following steps: forming adamaged region at a given depth from a surface of a single crystalsemiconductor substrate; performing plasma treatment to the surface ofthe single crystal semiconductor substrate; forming an insulating layeron a substrate having an insulating surface; bonding the single crystalsemiconductor substrate and the substrate having the insulating surfacewith the insulating layer interposed therebetween; performing heattreatment to the single crystal semiconductor substrate to separate thesingle crystal semiconductor substrate in the damaged region and to forma single crystal semiconductor layer over the substrate having theinsulating surface.

In the above steps, the insulating layer may be formed by a chemicalvapor deposition method using an organic silane gas. Further, aprotective film may be formed before forming the damaged region, and theprotective film may be removed after forming the damaged region.

Another feature of a method for manufacturing a semiconductor substrateof the present invention is to include the following steps: forming adamaged region at a given depth from a surface of a single crystalsemiconductor substrate; performing plasma treatment to the surface ofthe single crystal semiconductor substrate; forming a first insulatinglayer on the surface of the single crystal semiconductor substrate towhich the plasma treatment is performed; forming a second insulatinglayer in contact with the first insulating layer; bonding the singlecrystal semiconductor substrate and the first insulating layer, and asubstrate having an insulating surface with the second insulating layerinterposed therebetween; performing heat treatment to the single crystalsemiconductor substrate to separate the single crystal semiconductorsubstrate in the damaged region and to form a single crystalsemiconductor layer over the substrate having the insulating surface.

Another feature of a method for manufacturing a semiconductor substrateof the present invention is to include the following steps: forming adamaged region at a given depth from a surface of a single crystalsemiconductor substrate; performing plasma treatment to the surface ofthe single crystal semiconductor substrate; forming a first insulatinglayer on the surface of the single crystal semiconductor substrate towhich the plasma treatment is performed; forming a second insulatinglayer on a substrate having an insulating surface; bonding the singlecrystal semiconductor substrate and the first insulating layer, and thesubstrate having the insulating surface with the second insulating layerinterposed therebetween; performing heat treatment to the single crystalsemiconductor substrate to separate the single crystal semiconductorsubstrate in the damaged region and to form a single crystalsemiconductor layer over the substrate having the insulating surface.

In the above steps, the first insulating layer may be formed to have astacked-layer structure. Further, the first insulating layer may beformed to have a stacked-layer structure of a silicon onynitride layerand a silicon nitride oxide layer, and the silicon oxynitride layer maybe formed to be in contact with the single crystal semiconductorsubstrate.

The second insulating layer may be formed by a chemical vapor depositionmethod using an organic silane gas. Further, a protective film may beformed before forming the damaged region, and the protective film may beremoved after forming the damaged region.

In the above steps, the plasma treatment with an electron density of1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electron temperature of 0.2 eV to 2.0eV is preferably performed. Furthermore, the plasma treatment may beperformed under a hydrogen (H₂) atmosphere, an oxygen (O₂) atmosphere,or a mixed atmosphere of hydrogen and oxygen.

A semiconductor substrate can be provided by the aforementionedmanufacturing method.

By using the above semiconductor substrate, various semiconductordevices and electronic devices can be provided.

In this invention, the semiconductor devices include display devicessuch as a liquid crystal display device and an electroluminescencedisplay device; wireless tags referred to as an RFID (Radio FrequencyIDentification) tag, an RF tag, an RF chip, a radio processor, a radiomemory, an IC (Integrated Circuit) tag, an IC label, an electronic tag,and an electronic chip; microprocessors such as a central processingunit (CPU); integrated circuits; and other general semiconductor devicesin which a single crystal semiconductor layer formed by separating froma single crystal semiconductor substrate is used.

According to the present invention, a semiconductor substrate in which adefect in an interface between a single crystal semiconductor layer andan insulating layer is reduced can be provided. Furthermore, asemiconductor device and an electronic device with the use of thesemiconductor substrate can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1E are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIG. 2 is a diagram showing an apparatus used for manufacturing asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 3A to 3C are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 4A to 4C are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 5A to 5C are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 6A to 6D are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 7A to 7C are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 8A to 8C are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment Mode of thepresent invention;

FIGS. 9A and 9B are a plane view and a cross sectional view of asemiconductor device in connection with an Embodiment Mode of thepresent invention, respectively;

FIGS. 10A and 10B are a plane view and a cross sectional view of asemiconductor device in connection with an Embodiment Mode of thepresent invention, respectively;

FIG. 11 is a diagram showing a structure of a semiconductor device inconnection with an Embodiment Mode of the present invention;

FIG. 12 is a diagram showing a structure of a semiconductor device inconnection with an Embodiment Mode of the present invention;

FIGS. 13A to 13H are diagrams showing electronic devices usingsemiconductor devices in connection with an Embodiment Mode of thepresent invention;

FIGS. 14A to 14F are diagrams showing uses of semiconductor devices inconnection with an Embodiment Mode of the present invention;

FIGS. 15A to 15D are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment of the presentinvention; and

FIGS. 16A to 16C are diagrams showing a manufacturing process of asemiconductor substrate in connection with an Embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Mode

Embodiment Modes of the present invention are described hereinafter withreference to the drawings. Note that it will be easily understood bythose skilled in the art that the present invention can be embodied in awide variety of different ways and, therefore, various modifications andvariations can be made to the present invention without departing fromthe spirit and scope thereof. Thus, the present invention should not beconstrued as being limited to the description in the followingembodiment modes and example. Note that reference numerals denoting theidentical portions are the same in all figures in the followingdescription of the invention.

Embodiment Mode 1

In this embodiment mode, an example of a method for manufacturing asemiconductor device of the present invention is described withreference to FIGS. 1A to 3C.

First, a single crystal semiconductor substrate 100 is prepared. Then, asurface of the single crystal semiconductor substrate 100 is irradiatedwith ions to introduce the ions in a given depth from a top surface sothat a damaged region 102 (also referred to as an ion implanted layer oran ion doped layer) and a single crystal semiconductor layer 104 areformed (see FIG. 1A). As a formation method of the damaged region 102, amethod which is used when an impurity element is added to asemiconductor layer (an ion doping method), a method in which an ionizedgas is mass-separated to irradiate a semiconductor layer selectively (anion implantation method), or the like can be given. The irradiation withthe ions may be conducted in consideration of the thickness of thesingle crystal semiconductor layer 104 which is to be formed. Thethickness of the single crystal semiconductor layer 104 may be about 5nm to 500 nm, preferably 10 nm to 200 nm. The acceleration voltage toirradiate with the ions can be determined in consideration of the abovethickness.

The single crystal semiconductor substrate 100 is not particularlylimited as long as the substrate is formed of a single crystalsemiconductor material. As an example, a single crystal siliconsubstrate can be used. Besides, a substrate formed of a single crystalgermanium, a compound semiconductor such as gallium arsenide or anindium phosphide, or the like can be used.

As the ions used for irradiation, ions of halogen typified by fluorine,hydrogen, helium and the like are given. In the case of irradiating withfluorine ions as halogen ions, BF₃ may be used as a material gas. Forexample, in the case of using a single crystal silicon substrate as thesingle crystal semiconductor substrate 100 and irradiating the singlecrystal silicon substrate with halogen ions such as fluorine ions,microvoids are formed in the damaged region 102. This is because siliconatoms in a silicon crystal lattice are purged by the halogen ions. Bychanging the volume of the thus formed microvoids, the single crystalsilicon substrate can be separated. Specifically, the volumetric changeof the microvoids is induced by heat treatment at a low temperature.Note that hydrogen may be included in the microvoids by irradiating withhydrogen ions after irradiating with fluorine ions.

Furthermore, a plurality of ions formed of the same atom with differentmass number may be used for the irradiation. For example, in the case ofirradiating with hydrogen ions, H⁺, H₂ ⁺ and H₃ ⁺ are preferablyincluded, and the ratio of the H₃ ⁺ ions is preferably increased. Byincreasing the ratio of the H₃ ⁺ ions, irradiation efficiency can beincreased, and thus, irradiation time can be shortened.

Next, plasma treatment is performed to the surface of the single crystalsemiconductor layer 104 (see FIG. 1B). To be concrete, the plasmatreatment is performed under a hydrogen (H₂) atmosphere, an oxygen (O₂)atmosphere, or a mixed atmosphere of oxygen and hydrogen, and, thesurface of the single crystal semiconductor layer 104 is modified. Byperforming the plasma treatment under the hydrogen atmosphere, thesurface is etched and contaminant can be removed. Furthermore, one partof the surface of the single crystal semiconductor layer 104 can beremoved and an inner dense film can be exposed. Accordingly, danglingbonds in the single crystal semiconductor layer 104 can be terminated byhydrogen. Moreover, by performing the plasma treatment under the oxygenatmosphere, a dense oxygen film can be formed on the surface of thesingle crystal semiconductor layer 104. In other words, by performingthe plasma treatment under these atmospheres, the interface between thesingle crystal semiconductor layer 104 and a bonding layer to be formedlater can be kept clean and a defect can be reduced. An advantageouseffect which is similar to that of this embodiment mode can be obtainedeven if a rare gas element is added to the above atmospheres.

Here, a case where the plasma treatment is not performed to the surfaceof the single crystal semiconductor layer 104 is considered. In the casewhere the plasma treatment is not performed to the single crystalsemiconductor layer 104, a defect in an interface between the singlecrystal semiconductor layer 104 and the bonding layer exists; therefore,an interface state density is increased and a fixed charge is generated.An original characteristic of the single crystal semiconductor can notbe obtained from a semiconductor element (for example, a transistor)formed using such a single crystal semiconductor layer 104. Morespecifically, various problems such as fluctuation in a thresholdvoltage, reduction in mobility, increase in subthreshold swing (V_(g)which is necessary to increase I_(d) by an order of magnitude inI_(d)−V_(g) curve). The plasma treatment to the single crystalsemiconductor layer 104 is extremely effective to solve these problems.According to the present invention, the defect in the interface that isa source of the above-described problems can be reduced.

As a method for reducing the defect in the interface, there is a methodof forming an oxide film by a thermal oxidation method. However, hightemperature condition needed for thermal oxidation can not be applied toa Smart Cut method. In the Smart Cut method, separation of the singlecrystal semiconductor layer is conducted by heat treatment; however,temperature condition of the heat treatment is comparatively low atabout 400° C. to 600° C. On the other hand, temperature condition neededfor the thermal oxidation is 800° C. or higher, and in the case wheresuch a high temperature process is employed in the Smart Cut method,separation of the single crystal semiconductor layer 104 is advanced.For the foregoing reasons, it is apparent that the plasma treatment ispreferable to decrease the defects at the interface in the Smart Cutmethod.

As the plasma treatment, plasma treatment using a high frequency wave(such as a microwave) under the conditions of high density (preferably,in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³) and a low electrontemperature (preferably, in the range of 0.2 eV to 2.0 eV, morepreferably, in the range of 0.5 eV to 1.5 eV) is preferably performed(the plasma treatment is hereinafter referred to as high-density plasmatreatment). Such high density plasma treatment that features a lowelectron temperature has low kinetic energy of active species;therefore, damage due to plasma is less than the case of normal plasmatreatment. Therefore, a more favorable interface as compared with theone formed by the normal plasma treatment can be formed. The highdensity plasma treatment is preferably performed in a mixed atmosphereof hydrogen and a rare gas (helium (He), neon (Ne), argon (Ar), krypton(Kr), xenon (Xe), and the like), or a mixed atmosphere of oxygen,hydrogen, and a rare gas.

In this embodiment mode, an example of performing the plasma treatmentin the atmosphere containing at least hydrogen or oxide is described;however, the present invention is not limited to this. For example, theplasma treatment may be performed in an atmosphere containing nitrogenoxide (NO_(x)), ammonia (NH₃), nitrogen (N_(2,)), or the like, or in amixed atmosphere of any of these gases and hydrogen, oxygen, a rare gas,or the like.

FIG. 2 shows a structural example of an apparatus for performing plasmatreatment. This plasma treatment apparatus in FIG. 2 includes asupporting base 200 for disposing the single crystal semiconductorsubstrate 100 to which plasma treatment is to be performed, a gassupplying portion 202 for introducing a gas, an exhaust outlet 204connected to a vacuum pump for exhausting a gas, an antenna 206, adielectric plate 208, and a microwave supplying portion 210 forsupplying a microwave for generating plasma. In addition, by providingthe supporting base 200 with a temperature controlling portion 212, thetemperature of the single crystal semiconductor substrate 100 can becontrolled.

Hereinafter, a procedure of the plasma treatment is described. First, atreatment chamber is evacuated, and a plasma treatment gas containinghydrogen or oxygen is introduced through the gas supplying portion 202.Note that the gas is not limited to this. The single crystalsemiconductor substrate is set to have a temperature of about roomtemperature, or heated at a temperature of 100° C. to 400° C. by thetemperature controlling portion 212. The distance between the singlecrystal semiconductor substrate 100 and the dielectric plate 208(hereinafter also referred to as an “electrode distance”) is about 10 mmto 80 mm (preferably, 20 mm to 60 mm).

Next, microwaves (for example, 2.45 GHz) are supplied to the antenna 206from the microwave supplying portion 210. The microwaves are introducedinto the treatment chamber through the dielectric plate 208, wherebyplasma 214 is generated. By exciting plasma using the microwaves, plasmawith a low electron temperature and a high electron density can begenerated. In this embodiment mode, the case where the high-densityplasma treatment is performed using the microwaves is described;however, the present invention is not limited hereto.

Subsequently, a bonding layer 106 is formed over the single crystalsemiconductor layer 104 (see FIG. 1C). The bonding layer 106 ispreferably formed of a silicon oxide film by a chemical vapor depositionmethod (CVD method) using an organic silane gas. Alternatively, thebonding layer 106 may be formed of a silicon oxide film by a CVD methodusing a silane gas. In the case where the CVD method is used, it isnecessary to form a film under a temperature condition that adegasification of the damaged region 102 does not occur. When the singlecrystal semiconductor layer 104 is separated from the single crystalsemiconductor substrate 100, the heat treatment is performed at atemperature higher than film-formation temperature. In addition, thebonding layer 106 is formed of an insulating material, and therefore, itcan be also referred to as an insulating layer.

As the bonding layer 106, a silicon oxynitride film may be formed by anLPCVD method using SiH₄ and NO₂ as material gases. Accordingly, apreferable bonding layer 106 can be formed even under a low-temperaturecondition of 300° C. to 400° C. For example, a preferable bonding layercan be formed under the condition where the flow rate of SiH₄ is 40sccm, the flow rate of NO₂ is 400 sccm, pressure is 266.6 Pa, and thetemperature is 350° C.

The bonding layer 106 is formed to be smooth and has a hydrophilicsurface. As the bonding layer 106, a silicon oxide film is suitable.Specifically, a silicon oxide film manufactured by a CVD method using anorganic silane gas is preferably used. As the organic silane gas, acompound including silicon such as tetraethoxysilane (TEOS:Si(OC₂H₅)₄),trimethylsilane(CH₃)₃ SiH), Tetramethylcyclotetrasiloxane (TMCTS),octamethylcyclotetra siloxane (OMCTS), hexamethyldisilazane (HMDS),triethoxysilane (SiH(OC₂H₅)₃), and trisdimethylaminosilane(SiH(N(CH₃)₂)₃) can be used.

The bonding layer 106 is formed with a thickness of about 5 nm to 500nm. With such a thickness, a surface on which a film to be formed can besmoothed and the smoothness of the growing surface of the film can besecured as well. In addition, distortion of a substrate to be bondedwith the bonding layer 106 can be relieved. A substrate 110 having aninsulating surface to be formed later may be provided with a similarbonding layer. As described, a strong bond can be formed when a siliconoxide film formed of organic silane as a material is provided overeither one or both surfaces that are to form a bond.

Note that a structure in which an insulating layer including nitrogenmay be provided between the single crystal semiconductor layer 104 andthe bonding layer 106 may be employed. The insulating layer includingnitrogen can be formed of one or more materials selected from siliconnitride, silicon nitride oxide, or silicon oxynitride. Note that theinsulating layer including nitrogen has either a single layer structureor a stacked-layer structure. For example, the insulating layerincluding nitrogen may be formed by stacking a silicon oxynitride filmand a silicon nitride oxide film from the side of the single crystalsemiconductor layer 104. The insulating layer including nitrogen isprovided so as to prevent an impurity of movable ions such as alkalimetal and alkaline earth metal, moisture, and the like from entering thesingle crystal semiconductor layer 104. An insulating layer other thanthe insulating layer including nitrogen may be provided as long as itcan prevent the impurity from entering.

Note that a silicon oxynitride means the one that contains more oxygenthan nitrogen and includes, for example, oxygen, nitrogen, silicon, andhydrogen at concentrations ranging from greater than or equal to 50atomic % and less than or equal to 70 atomic %, greater than or equal to0.5 atomic % and less than or equal to 15 atomic %, greater than orequal to 25 atomic % and less than or equal to 35 atomic %, and greaterthan or equal to 0.1 atomic % and less than or equal to 10 atomic %,respectively. Further, a silicon nitride oxide means the one thatcontains more nitrogen than oxygen and includes, for example, oxygen,nitrogen, silicon, and hydrogen at concentrations ranging from greaterthan or equal to 5 atomic % and less than or equal to 30 atomic %,greater than or equal to 20 atomic % and less than or equal to 55 atomic%, greater than or equal to 25 atomic % and less than or equal to 35atomic %, and greater than or equal to 10 atomic % and less than orequal to 25 atomic %, respectively. Note that the above ranges are thecases where measurements are performed using Rutherford backscatteringspectrometry (RBS) and hydrogen forward scattering (HFS). The total ofpercentages of the constituent elements does not exceed 100 atomic %.

Then, the substrate 110 having the insulating surface is disposed incontact with the bonding layer 106 (see FIG. 1D). The substrate 110having the insulating surface is disposed in contact with the bondinglayer 106 and pressure is applied thereto, and therefore, a strong bondcan be formed. Note that heat treatment is preferably performed afterbonding the substrate 110 having the insulating surface and the singlecrystal semiconductor substrate 100 with the bonding layer 106interposed therebetween. By performing the pressure treatment and theheat treatment, bonding strength can be improved.

In order to form a favorable bond, the surfaces which are to form a bondmay be activated. For example, the surfaces which are to form the bondare irradiated with an atomic beam or an ion beam. In the case of usingthe atomic beam or the ion beam, an atomic beam of an inert gas such asargon or an ion beam of an inert gas can be used. Alternatively, plasmatreatment or radical treatment may be performed. By such surfacetreatment, a bond between layers of different materials can be formed ata low temperature of about 200° C. to 400° C.

For the substrate 110 having the insulating surface, any of a variety ofglass substrates which are used in the electronics industry such as analuminosilicate glass substrate, an aluminoborosilicate glass substrate,and a barium borosilicate glass substrate; a quartz substrate; a ceramicsubstrate; a sapphire substrate; or the like can be used. A glasssubstrate is preferably used, and a mother glass substrate having alarge area can be also used, such as a so-called sixth generationsubstrate (1500 mm×1850 mm), a so-called seventh generation substrate(1870 mm×2200 mm), and a so-called eighth generation substrate (2200mm×2400 mm), for example. By using the mother glass substrate having thelarge area as the substrate 110 having the insulating surface, the areaof the semiconductor substrate can be enlarged. However, the substrate110 having the insulating surface is not limited to the above mentionedsubstrates. For example, a substrate formed of a resin material can alsobe used as long as the substrate has an allowable temperature limit.

Subsequently, heat treatment is performed so as to separate the singlecrystal semiconductor layer 104 from the single crystal semiconductorsubstrate 100 using the damaged region 102 as a separation surface (seeFIG. 1E). For example, by performing the heat treatment at a temperatureof 400° C. to 600° C., volume change of microvoids formed in the damagedregion 102 is induced and the single crystal semiconductor layer 104 isseparated from the single crystal semiconductor substrate 100. Becausethe bonding layer 106 is bonded to the substrate 110 having theinsulating surface, the single crystal semiconductor layer 104 havingthe same crystallinity as the single crystal semiconductor substrate 100remains on the substrate 110 having the insulating surface.

In the case of using the glass substrate as the substrate 110 having theinsulating surface, the heat treatment is performed at a temperatureclose to a strain point of the glass substrate, specifically at atemperature in a range of minus 50° C. to plus 50° C. of the strainpoint of the glass substrate, and more specifically, at a temperature ina range from 580° C. to 680° C. The glass substrate has a characteristicof shrinking when heated. Therefore, by heating the glass substrate at atemperature close to a strain point of the glass substrate, specificallyat a temperature approximately in the range of minus 50° C. to plus 50°C. (or higher) of the strain point of the glass substrate, shrink of theglass substrate in later heat treatment can be suppressed. Thus, evenwhen heat treatment is conducted to the glass substrate to which asingle crystal semiconductor layer having a different coefficient ofthermal expansion is bonded, film separation of the single crystalsemiconductor layer from the glass substrate can be prevented. Moreover,deformation such as warping of the glass substrate and the singlecrystal semiconductor layer can be prevented.

In the case of using the glass substrate, after heating the glasssubstrate, it is preferable to avoid rapid cooling. Specifically, theglass substrate may be cooled down to a temperature equal to or lowerthan the strain point, preferably at a rate of 2° C./min or lower, morepreferably at a rate of 0.5° C./min or lower, and further preferably at0.3° C./min or lower. By setting the temperature reduction rate low,local stress generated when the glass substrate shrinks can be relieved.This heat treatment may be conducted under an atmospheric pressure or areduced pressure, and the atmosphere may be properly set and may be anitrogen atmosphere, an oxygen atmosphere, or the like. Note that theheat treatment is applicable to the substrate other than the glasssubstrate in the case where substrate has a characteristic of shrinkingafter being heated.

Note that the heat treatment in the bonding step and the heat treatmentin the separating step can be performed at the same time. In this case,two steps can be performed in one heat treatment; and therefore, thenumber of manufacturing step can be reduced, so that the semiconductorsubstrate can be manufactured at low cost.

Note that the single crystal semiconductor layer 104 obtained by theaforementioned steps is preferably subjected to chemical mechanicalpolishing (CMP) in order to flatten the surface thereof. By improvingflatness of the single crystal semiconductor layer 104, variation in thesemiconductor elements that are to be formed later can be suppressed.Note that CMP may be omitted when a desired characteristic is obtained.

Moreover, by conducting another heat treatment or laser irradiation, thecharacteristic of the single crystal semiconductor layer 104 may beimproved. The allowable temperature limit of the substrate 110 havingthe insulating surface is used as a measure of the heat treatmenttemperature. In the case of using a glass substrate as the substrate 110having the insulating surface, a distortion point of the glass substrateis used as a measure of the heat treatment temperature. Specifically,the heat treatment is performed at a temperature approximately in arange from minus 50° C. to plus 50° C. of the distortion point of theglass substrate (more specifically, 580° C. to 680° C.).

For the laser irradiation, for example, a continuous wave laser (a CWlaser), a quasi-continuous wave laser (a pulsed laser with a repetitionrate of 10 MHz or more, preferably, 80 MHz or more), or the like can beused. Specifically, as the CW laser, an Ar laser, a Kr laser, a CO₂laser, a YAG laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, a GdVO₄laser, a Y₂O₃ laser, a ruby laser, an alexandrite laser, a Ti: sapphirelaser, a helium cadmium laser, and the like can be used. As the quasi-CWlaser, a pulsed laser such as an Ar laser, a Kr laser, an excimer laser,a CO₂ laser, a YAG laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, aGdVO₄ laser, a Y₂O₃ laser, a ruby laser, an alexandrite laser, a Ti:sapphire laser, a copper vapor laser, and a gold vapor laser can beused. Such a pulsed laser can be treated in the same way as thecontinuous wave laser when the repetition rate is increased.

Then, a case where the bonding layer 106 is provided for the side of thesubstrate 110 having the insulating surface is described with referenceto FIGS. 3A to 3C. Note that steps up to the plasma treatment shown inFIG. 1B are similar in FIGS. 3A to 3C; therefore, detailed explanationthereof is omitted.

After performing the plasma treatment to the single crystalsemiconductor layer 104 (see FIG. 3A), a substrate 110 having aninsulating surface over which a barrier layer 300 and a bonding layer106 are formed, is disposed in contact with the single crystalsemiconductor substrate 100 (see FIG. 3B). Specifically, the bondinglayer 106 and the single crystal semiconductor layer 104 to which theplasma treatment is performed are disposed in contact and bonded to eachother. The barrier layer 300 is provided so as to prevent impuritiessuch as alkali metal and alkaline earth metal from entering the singlecrystal semiconductor layer 104. The barrier layer 300 is notnecessarily provided when intrusion of the impurities from the substrate110 having the insulating surface into the single crystal semiconductorlayer 104 does not cause any problems.

The barrier layer 300 can be formed of one or a plurality of materialsselected from silicon oxide, silicon nitride, silicon nitride oxide,silicon oxynitride, and the like. The barrier layer 300 may have asingle layer structure or a stacked layer structure. Note that thematerials for forming the barrier layer 300 are not limited to theaforementioned materials, as long as the materials can prevent animpurity from entering. The barrier layer 300 is formed of an insulatingmaterial; therefore, it can also be referred to as an insulating layer.

Thereafter the single crystal semiconductor substrate 100 is separated(see FIG. 3C). The heat treatment when the single crystal semiconductorsubstrate 100 is separated can be carried out similarly to that in thecase of FIG. 1E; therefore, detailed description is omitted.Accordingly, a semiconductor substrate shown in FIG. 3C can be obtained.

It is preferable that the semiconductor substrate shown in FIG. 3C isalso subjected to chemical mechanical polishing (CMP). By improvingflatness of the single crystal semiconductor layer 104, variation ofsemiconductor elements to be formed later can be suppressed. Note thatCMP may be omitted when a desired characteristic is obtained.

By conducting another heat treatment or laser irradiation, thecharacteristic of the single crystal semiconductor layer 104 may beimproved. For the heat treatment temperature and a laser capable ofbeing used, the above description can be referred to; therefore,description is omitted.

Accordingly, a semiconductor substrate in which a defect in an interfacebetween the single crystal semiconductor layer 104 and the bonding layer106 is reduced can be provided. Thus, a semiconductor device in which acharacteristic of a semiconductor element to be formed later isdrastically improved can be provided.

Embodiment Mode 2

In this embodiment mode, another example of a method for manufacturing asemiconductor device according to the present invention is describedwith reference to FIGS. 4A to 4C and FIGS. 5A to 5C. In this embodimentmode, a method for manufacturing a semiconductor device in which thedefect shown in Embodiment Mode 1 can be repaired and damage of a singlecrystal semiconductor layer due to ion irradiation can be reduced isdescribed.

First, a protective layer 450 is formed over a single crystalsemiconductor substrate 400 (see FIG. 4A). Any substrate can be used asthe single crystal semiconductor substrate 400 as long as it is formedof a single crystal semiconductor material. As an example, a singlecrystal silicon substrate can be used. Besides, a substrate formed of asingle crystal germanium, a compound semiconductor such as galliumarsenide, and indium phosphide, or the like can be used.

The protective layer 450 can be formed of one or a plurality ofmaterials selected from silicon oxide, silicon nitride, silicon nitrideoxide, silicon oxynitride, and the like. The protective layer 450 mayhave a single layer structure or a stacked layer structure. As themethod for forming the protective layer 450, a chemical vapor deposition(CVD) method, a sputtering method, a thermal oxidation method, a thermalnitridation method, or the like is given. However, the method is notlimited to this. It is preferable that the thickness of the protectivelayer 450 is approximately 50 nm to 200 nm. The protective layer 450 isformed of an insulating material; therefore, it can also be referred toas an insulating layer. By providing the protective layer 450, roughnessof the surface of the single crystal semiconductor substrate 400 (thesurface of the single crystal semiconductor layer to be formed later)caused by ion irradiation can be suppressed.

Then, the surface of the single crystal semiconductor substrate 400 isirradiated with ions through the protective layer 450 to introduce theions in a given depth from the surface, thereby forming a damaged region402 and a single crystal semiconductor layer 404 (see FIG. 4B).Embodiment Mode 1 can be referred to for the detail of the method formanufacturing the damaged region 402 and the single crystalsemiconductor layer 404; therefore detailed description is omitted.

After forming the damaged region 402, the protective layer 450 isremoved and plasma treatment is performed to the surface of the singlecrystal semiconductor layer 404 (see FIG. 4C). To be concrete, theplasma treatment is performed under a hydrogen (H₂) atmosphere, or amixed atmosphere of oxygen (O₂) and hydrogen so as to modify the surfaceof the single crystal semiconductor layer 404. Accordingly, contaminanton the surface of the single crystal semiconductor layer 404 can beremoved and a dense surface can be formed, and thus, a defect in theinterface between the single crystal semiconductor layer 404 and abonding layer to be formed later can be reduced. In this embodimentmode, damage to the surface of the single crystal semiconductor layer404 due to ion irradiation is reduced by the protective layer 450.However, a certain defect remains. Therefore, by removing the protectivelayer 450 and performing plasma treatment to the single crystalsemiconductor layer 404, defect can be further reduced.

In addition, the protective layer 450 itself is damaged by ionirradiation. In this embodiment mode, the protective layer 450 is notleft and is removed entirely; therefore, a semiconductor substrate notusing a deteriorated protective layer can be manufactured. By removingthe deteriorated protective layer, the semiconductor substrate havingfurther improved characteristics can be realized.

Embodiment Mode 1 can be referred to for the detail of the plasmatreatment; therefore, description is omitted.

Subsequently, a bonding layer 406 is formed over the single crystalsemiconductor layer 404 to which the plasma treatment is performed (seeFIG. 5A). The bonding layer 406 is preferably formed of a silicon oxidefilm by chemical vapor deposition method (CVD method) using an organicsilane gas. Alternatively, the bonding layer 406 may be formed of asilicon oxide film by a CVD method using a silane gas. In the case wherethe CVD method is used, it is necessary to form a film under a conditionthat a degasification of the damaged region 402 does not occur. When thesingle crystal semiconductor layer 404 is separated from the singlecrystal semiconductor substrate 400, heat treatment is performed at atemperature higher than film-formation temperature. In addition, thebonding layer 406 is formed of an insulating material; therefore, it canbe also referred to as an insulating layer.

Embodiment Mode 1 can be referred to for the detail of the method formanufacturing the bonding layer 406; therefore, description is omitted.

Note that a structure in which an insulating layer including nitrogenmay be provided between the single crystal semiconductor layer 404 andthe bonding layer 406 may be employed. The insulating layer includingnitrogen can be formed of one or more materials selected from siliconnitride, silicon nitride oxide, or silicon oxynitride. Note that theinsulating layer including nitrogen has either a single layer structureor a stacked-layer structure. For example, the insulating layerincluding nitrogen may be formed by stacking a silicon oxynitride filmand a silicon nitride oxide film from the side of the single crystalsemiconductor layer 404. The insulating layer including nitrogen isprovided so as to prevent an impurity of movable ions such as alkalimetal and alkaline earth metal, moisture, and the like from entering thesingle crystal semiconductor layer 404. An insulating layer other thanthe insulating layer including nitrogen may be provided as long as itcan prevent the impurity from entering.

Then, a substrate 410 having an insulating surface is disposed incontact with the bonding layer 406 (see FIG. 5B). The substrate 410having the insulating surface is disposed in contact with the bondinglayer 406 and pressure is applied thereto, and therefore, a strong bondcan be formed. Note that heat treatment is preferably performed afterbonding the substrate 410 having the insulating surface and the singlecrystal semiconductor substrate 400 with the bonding layer 406interposed therebetween. By performing the pressure treatment and theheat treatment, bonding strength can be improved.

In order to form a favorable bond, the surfaces which are to form a bondmay be activated. For example, the surfaces which are to form the bondare irradiated with an atomic beam or an ion beam. In the case of usingthe atomic beam or the ion beam, an atomic beam of an inert gas such asargon or an ion beam of an inert gas can be used. Alternatively, plasmatreatment or radical treatment may be performed. By such surfacetreatment, a bond between layers of different materials can be formed ata low temperature of about 200° C. to 400° C.

For the substrate 410 having the insulating surface, any of a variety ofglass substrates which are used in the electronics industry such as analuminosilicate glass substrate, an aluminoborosilicate glass substrate,and a barium borosilicate glass substrate; a quartz substrate; a ceramicsubstrate; a sapphire substrate; or the like can be used. A glasssubstrate is preferably used, and a mother glass substrate having alarge area can be also used, such as a so-called sixth generationsubstrate (1500 mm×1850 mm), a so-called seventh generation substrate(1870 mm×2200 mm), and a so-called eighth generation substrate (2200mm×2400 mm), for example. By using the mother glass substrate having thelarge area as the substrate 410 having the insulating surface, the areaof the semiconductor substrate can be enlarged. However, the substrate410 having the insulating surface is not limited to the above mentionedsubstrates. For example, a substrate formed of a resin material can alsobe used as long as the substrate has an allowable temperature limit.

Subsequently, heat treatment is performed so as to separate the singlecrystal semiconductor layer 404 from the single crystal semiconductorsubstrate 400 using the damaged region 402 as a separation surface (seeFIG. 5C). For example, by performing the heat treatment at a temperatureof 400° C. to 600° C., volume change of microvoids formed in the damagedregion 402 is induced and the single crystal semiconductor layer 404 isseparated from the single crystal semiconductor substrate 400. Becausethe bonding layer 406 is bonded to the substrate 410 having theinsulating surface, the single crystal semiconductor layer 404 havingthe same crystallinity as the single crystal semiconductor substrate 400remains on the substrate 410 having the insulating surface.

Embodiment Mode 1 can be referred to for the detail of the heattreatment in a separation step. Note that the heat treatment in thebonding step and the heat treatment in the separating step can beperformed at the same time. In this case, two steps can be performed inone heat treatment; and therefore, the number of manufacturing steps canbe reduced, so that the semiconductor substrate can be manufactured atlow cost.

Note that the single crystal semiconductor layer 404 obtained by theaforementioned steps is preferably subjected to chemical mechanicalpolishing (CMP) in order to flatten the surface thereof. By improvingflatness of the single crystal semiconductor layer 404, variation in thesemiconductor elements that are to be formed later can be suppressed.Note that CMP may be omitted when a desired characteristic is obtained.

Moreover, by conducting another heat treatment or laser irradiation, thecharacteristic of the single crystal semiconductor layer 404 may beimproved. Embodiment Mode 1 can be referred to for heat treatmenttemperature and a laser to be used.

Also in this embodiment mode, similarly to Embodiment Mode 1, asemiconductor substrate can be manufactured by providing the bondinglayer 406 at the side of the substrate 410 having the insulatingsurface. In this case, after the steps up to plasma treatment shown inFIG. 4C are performed, a process in FIGS. 3A to 3C is performed.

As described, a semiconductor substrate in which a defect in aninterface between the single crystal semiconductor layer 404 and thebonding layer 406 is reduced can be provided. Accordingly, asemiconductor device in which a characteristic of a semiconductorelement to be formed later is drastically improved can be provided. Inthis embodiment mode, by providing the protective layer 450, damage tothe single crystal semiconductor layer 404 due to ion irradiation isreduced. As a result, the defect can be reduced, and a characteristic inthe semiconductor element can be further improved. Moreover, theprotective layer 450 is removed after the ion irradiation, thedeteriorated protective layer 450 is not left; therefore, asemiconductor substrate having an extremely favorable characteristic canbe provided.

This embodiment mode can be appropriately combined with Embodiment Mode1.

Embodiment Mode 3

In this embodiment mode, an example of a method for manufacturing asemiconductor device of the present invention is described withreference to FIGS. 6A to 6D to FIGS. 9A and 9B. In this embodiment mode,a liquid crystal display device is described as an example of thesemiconductor device; however, the semiconductor device of the inventionis not limited to this.

First, a single crystal semiconductor layer is formed over a substratehaving an insulating surface using any of the methods shown inEmbodiment Mode 1 or Embodiment Mode 2 (see FIG. 6A). Here, a structurein which a barrier layer 602, a bonding layer 604, and a single crystalsemiconductor layer 606 are provided in order over a substrate 600having an insulating surface is described; however, the invention is notlimited to this. Then, the single crystal semiconductor layer 606 andthe bonding layer 604 are patterned into a desired shape, therebyforming island-shaped single crystal semiconductor layers.

As an etching process in patterning, either plasma etching (dry etching)or wet etching can be used. For treating a large-sized substrate, plasmaetching is suitable. As an etching gas, a fluorine-based gas such as CF₄or NF₃ or a chlorine-based gas such as Cl₂ or BCl₃ is used, and an inertgas such as He or Ar may be appropriately added thereto. When theetching is performed by an atmospheric pressure discharge, electricdischarging can be performed locally, and therefore, a mask layer doesnot need to be formed over the entire surface of a substrate.

After patterning the single crystal semiconductor layer 606 and thebonding layer 604, a p-type impurity such as boron, aluminum, or galliumis preferably added thereto in order to control the threshold voltage.For example, as the p-type impurity, boron can be added at aconcentration of 5×10¹⁷ atoms/cm³ to 1×10¹⁸ atoms/cm³.

A silicon nitride layer and a silicon oxide layer are formed as thebarrier layer 602 in a stacked-layer structure over the substrate 600having the insulating surface. By providing the barrier layer 602,contamination of the single crystal semiconductor layer 606 due tomovable ions can be prevented. Note that a silicon nitride oxide layer,an aluminum nitride layer, or an aluminum nitride oxide layer may beused instead of using the silicon nitride layer.

Then, a gate insulating layer 608 covering the island-shaped singlecrystal semiconductor layer is formed (see FIG. 6B). Here, theisland-shaped semiconductor layers formed by patterning are referred toas single crystal semiconductor layers 610, 612, and 614, respectively,for the sake of convenience. The gate insulating layer 608 is formed ofan insulating film containing silicon at a thickness of approximately 10nm to 150 nm by a plasma CVD method, a sputtering method, or the like.Specifically, the gate insulating layer 608 may be formed by using amaterial such as an oxide material or nitride material of silicon,typified by silicon nitride, silicon oxide, silicon oxynitride, andsilicon nitride oxide. Note that the gate insulating layer 608 may havea single layer structure or a stacked layer structure. Further, a thinsilicon oxide film with a thickness of 1 nm to 100 nm, preferably 1 nmto 10 nm, or more preferably 2 nm to 5 nm may be formed between thesingle semiconductor layer and the gate insulating layer. In order toform a gate insulating film having less gate leakage current at a lowtemperature, a rare gas element such as argon may be contained in areaction gas.

Next, a first conductive film and a second conductive film, which serveas gate electrode layers, are stacked over the gate insulating layer608. The first conductive film may be formed with a thickness of about20 nm to 100 nm, and the second conductive film may be formed with athickness of about 100 nm to 400 nm. In addition, the first conductivefilm and the second conductive film can be formed by a sputteringmethod, an evaporation method, a CVD method, or the like. The firstconductive film and the second conductive film may be formed of anelement selected from tantalum (Ta), tungsten (W), titanium (Ti),molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), or neodymium(Nd), an alloy material or a compound material containing the element asits main component, or the like. Further, for the first and secondconductive films, a semiconductor film typified by a polycrystal siliconfilm doped with an impurity element such as phosphorus; an AgPdCu alloy,or the like may be used. This embodiment mode is described using atwo-layer structure; however, the invention is not limited to thisstructure. And a stacked-layer structure of three or more layers or asingle layer structure may be used.

Then, a mask 616 a, a mask 616 b, a mask 616 c, a mask 616 d, and a mask616 e each of which is formed of a resist material are formed by aphotolithography method. The first conductive film and the secondconductive film are processed into a desired shape using the abovemasks, thereby forming a first gate electrode layer 618 a, a first gateelectrode layer 618 b, a first gate electrode layer 618 c, a first gateelectrode layer 618 d, a first conductive layer 618 e, a conductivelayer 620 a, a conductive layer 620 b, a conductive layer 620 c, aconductive layer 620 d, and a conductive layer 620 e (see FIG. 6C).

Etching can be performed to form a desired tapered shape by an ICP(Inductively Coupled Plasma) etching method with appropriate control ofthe etching conditions (e.g., the amount of electric energy applied to acoiled electrode layer, the amount of electric energy applied to anelectrode layer on the substrate side, and the electrode temperature onthe substrate side). An angle and the like of the tapered shape may alsobe controlled by the shape of the masks. Further, as an etching gas, thefollowing can be appropriately used: a chlorine-based gas typified byCl₂, BCl₃, SiCl₄, or CCl₄; a fluorine-based gas typified by CF₄, SF₆, orNF₃; or O₂. In this embodiment mode, the second conductive film isetched using an etching gas containing CF₄, Cl₂, and O₂, and the firstconductive film is successively etched using an etching gas containingCF₄ and Cl₂.

Subsequently, the conductive layer 620 a, the conductive layer 620 b,the conductive layer 620 c, the conductive layer 620 d, and theconductive layer 620 e are processed into a desired shape using the mask616 a, the mask 616 b, the mask 616 c, the mask 616 d, and the mask 616e. At this time, etching is conducted with an etching condition of highselectivity of the second conductive film which forms the conductivelayers with respect to the first conductive film which forms the firstgate electrode layers and the first conductive layer. A second gateelectrode layer 622 a, a second gate electrode layer 622 b, a secondgate electrode layer 622 c, a second gate electrode layer 622 d, and asecond conductive layer 622 e are formed by this etching. In thisembodiment mode, the second gate electrode layers and the secondconductive layer also have a tapered shape, in which a taper angle islarger than that of the first gate electrode layers 618 a, 618 b, 618 c,and 618 d and the first conductive layer 618 e. Here, “taper angle”refers to an angle formed by the meeting of a bottom surface with a sidesurface of an object. Thus, when the taper angle is 90°, the conductivelayer has a perpendicular side surface to the bottom surface of theconductive layer. By setting the taper angle to smaller than 90°,coverage of a film to be stacked thereover is improved and a defect isreduced. In this embodiment mode, Cl₂, SF₆, and O₂ are used as anetching gas for forming the second gate electrode layers and the secondconductive layer.

Through the aforementioned steps, a gate electrode layer 624 a and agate electrode layer 624 b can be formed in a peripheral driver circuitregion 680, and a gate electrode layer 624 c, a gate electrode layer 624d, and a conductive layer 624 e can be formed in a pixel region 690 (seeFIG. 6D). Note that the masks 616 a, 616 b, 616 c, 616 d, and 616 e areremoved after the aforementioned steps.

Next, an impurity element which imparts n-type conductivity is addedusing the gate electrode layers 624 a, 624 b, 624 c, and 624 d as masksto form first n-type impurity regions 626 a, 626 b, 628 a, 628 b, 630 a,630 b, and 630 c (see FIG. 7A). In this embodiment mode, doping isperformed by using phosphine (PH₃) as a doping gas containing animpurity element. Here, phosphorus (P) that is an impurity elementimparting n-type conductivity is added to the first n-type impurityregions at a concentration of about 1×10¹⁷ atoms/cm³ to 5×10¹⁸atoms/cm³.

Next, a mask 632 a, a mask 632 b, and a mask 632 c for covering thesingle crystal semiconductor layers 610 and a part of the single crystalsemiconductor layer 614 are formed. Then, an impurity element whichimparts n-type conductivity is added using the masks 632 a, 632 b, and632 c, and the second gate electrode layer 622 b as masks. As a result,a second n-type impurity region 634 a, a second n-type impurity region634 b, a third n-type impurity region 636 a, a third n-type impurityregion 636 b, a second n-type impurity region 640 a, a second n-typeimpurity region 640 b, a second n-type impurity region 640 c, a thirdn-type impurity region 642 a, a third n-type impurity region 642 b, athird n-type impurity region 642 c, and a third n-type impurity region642 d are formed. In this embodiment mode, doping is performed by usingphosphine (PH₃) as a doping gas containing an impurity element. Here,phosphorus (P) that is an impurity element imparting n-type conductivityis added to the second n-type impurity regions at a concentration ofabout 5×10¹⁹ atoms/cm³ to 5×10²⁰ atoms/cm³. An impurity element whichimparts n-type conductivity is added to the third n-type impurityregions 636 a and 636 b so as to contain the n-type impurity element atabout the same concentration as or at a slightly higher concentrationthan the third n-type impurity regions 642 a to 642 d. Furthermore, achannel formation region 638, a channel formation region 644 a, and achannel formation region 644 b are formed (see FIG. 7B).

The second n-type impurity regions are high-concentration impurityregions and function as source regions or drain regions. On the otherhand, the third n-type impurity regions are low-concentration impurityregions and function as so-called lightly doped drain (LDD) regions. Thethird n-type impurity regions 636 a and the 636 b are formed so as to beoverlapped with the first gate electrode layer 618 b. Accordingly, anelectric field around a source or a drain can be relieved anddeterioration of on-current due to hot carriers can be suppressed. Onthe other hand, the third n-type impurity regions 642 a to 642 d are notoverlapped with the gate electrode layers 624 c and 624 d, which has aneffect to reduce an off current.

Next, the masks 632 a, 632 b, and 632 c are removed, and masks 646 a and646 b which cover the single crystal semiconductor layers 612 and 614are formed. An impurity element which imparts p-type conductivity isadded using the masks 646 a and 646 b, and the gate electrode layer 624a as masks to form first p-type impurity regions 648 a and 648 b andsecond p-type impurity regions 650 a and 650 b. In this embodiment mode,doping is performed using diborane (B₂H₆) as a doping gas including animpurity element. Here, boron (B) which is an impurity element impartingp-type conductivity is added to the first p-type impurity regions andthe second p-type impurity regions at a concentration of about 1×10²⁰atoms/cm³ to 5×10²¹ atoms/cm³. Further, a channel formation region 652is formed (see FIG. 7C).

The first p-type impurity regions are high-concentration impurityregions and each function as a source or a drain. On the other hand, thesecond p-type impurity regions are low-concentration impurity regions,which are so-called lightly doped drain (LDD) regions.

Then, the masks 646 a and 646 b are removed. After the masks areremoved, an insulating film may be formed to cover the side surfaces ofthe gate electrode layers. The insulating film can be formed by a plasmaCVD method or a low pressure CVD (LPCVD) method. Heat treatment, intenselight irradiation, or laser light irradiation may be performed toactivate the impurity elements.

Subsequently, an interlayer insulating layer which covers the gateelectrode layers and the gate insulating layer is formed. In the presentembodiment mode, a stacked-layer structure of insulating films 654 and656 is employed (see FIG. 8A). A silicon nitride oxide film is formed asthe insulating film 654 with a thickness of 100 nm and a siliconoxynitride film is formed as the insulating film 656 with a thickness of900 nm. In this embodiment mode, the interlayer insulating layer has atwo-layer stacked structure; however, it may have a single layerstructure or a stacked structure including three or more layers. In thisembodiment mode, the insulating films 654 and 656 are sequentiallyformed by a plasma CVD method. Note that the materials of the insulatingfilms 654 and 656 are not limited to the above materials.

The insulating films 654 and 656 can be formed using a material selectedfrom substances including silicon oxide, silicon nitride, aluminumoxide, aluminum nitride, aluminum oxynitride, aluminum nitride oxidehaving a higher content of nitrogen than that of oxygen, diamond-likecarbon (DLC), carbon film containing nitrogen, and other inorganicinsulating materials. Further, a siloxane resin may be used as well. Asiloxane resin is a resin having a Si—O—Si bond. Siloxane has a skeletonstructure formed by a bond of silicon (Si) and oxygen (O) and has anorganic group containing at least hydrogen (for example, an alkyl groupor an aryl group) as a substituent. Alternatively, a fluoro group may beused as a substituent, or both a fluoro group and an organic groupcontaining at least hydrogen can be used as a substituent. Further, anorganic insulating material such as polyimide, acrylic, polyamide,polyimide amide, benzocyclobutene, or polysilazane can be used.

Next, contact holes (openings) that reach the single crystalsemiconductor layers and the gate electrode layers are formed in theinsulating films 654 and 656 and the gate insulating layer 608, using aresist mask. Etching may be performed once or plural times according toetching selectivity of a material to be used. In the present embodimentmode, first etching is performed with a condition that the insulatingfilm 656 that is a silicon oxynitride film, the insulating film 654 thatis a silicon nitride oxide film, and the gate insulating layer 608 haveselectivity, and the insulating film 656 is removed. Then, a secondetching is performed to remove the insulating film 654 and the gateinsulating layer 608, and the openings which reach source and drainregions are formed.

Then, a conductive film is formed to cover the openings, and theconductive film is etched. Therefore, a source electrode layer or adrain electrode layer 658 a, a source electrode layer or a drainelectrode layer 658 b, a source electrode layer or a drain electrodelayer 660 a, a source electrode layer or a drain electrode layer 660 b,a source electrode layer or a drain electrode layer 662 a, and a sourceelectrode layer or a drain electrode layer 662 b, each of which iselectrically connected to a part of a source region or a drain region,respectively are formed. For the each source electrode layer or drainelectrode layer, one or a plurality of elements selected from aluminum(Al), tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten (W),neodymium (Nd), chromium (Cr), nickel (Ni), platinum (Pt), gold (Au),silver (Ag), copper (Cu), magnesium (Mg), scandium (Sc), cobalt (Co),nickel (Ni), zinc (Zn), niobium (Nb), silicon (Si), phosphorus (P),boron (B), arsenic (As), gallium (Ga), indium (In), and tin (Sn); acompound or alloy material that contains one of the given elements asits main component (for example, indium tin oxide (ITO), indium zincoxide (IZO), indium tin oxide that contains silicon oxide (ITSO), zincoxide (ZnO), aluminum-neodymium (Al—Nd), magnesium-silver (MgAg), or thelike); a material that is a combination of any of these compounds; orthe like can be used. In addition to what is given above, a silicide(for example, aluminum-silicon, molybdenum-silicon, or nickel silicide),a compound that contains nitrogen (for example, titanium nitride,tantalum nitride, or molybdenum nitride), silicon (Si) doped with animpurity element such as phosphorus (P) or the like, or the like may beused.

Through the above steps, a p-channel thin film transistor 664 and ann-channel thin film transistor 666, and an n-channel thin filmtransistor 668 and a capacitor wiring 670 are formed in the peripheraldriver circuit region 680 and the pixel region 690, respectively (seeFIG. 8B).

Next, an insulating film 672 is formed as a second interlayer insulatinglayer. The insulating film 672 can be formed of a material selected fromsubstances including silicon oxide, silicon nitride, silicon oxynitride,silicon nitride oxide, aluminum oxide, aluminum nitride, aluminumoxynitride, aluminum nitride oxide having a higher content of nitrogenthan that of oxygen, diamond-like carbon (DLC), a nitrogen-containingcarbon film, PSG (phosphosilicate glass), BPSG (borophosphosilicateglass), an alumina film, polysilazane, and other inorganic insulatingmaterials. Further, a siloxane resin may be used as well. An organicinsulating material such as polyimide, acrylic, polyamide, polyimideamide or benzocyclobutene may also be used.

In this embodiment mode, since an interlayer insulating layer providedfor planarization needs to have high heat resistance, a high insulatingproperty, and a high level of planarity, the interlayer insulating layeris preferably formed by a coating method typified by a spin coatingmethod.

Subsequently, a contact hole is formed in the insulating film 672 of thepixel region 690, and a pixel electrode layer 674 is formed (see FIG.8C). The pixel electrode layer 674 can be formed using indium tin oxide(ITO), indium zinc oxide (IZO) in which indium oxide is mixed with zincoxide, a conductive material in which indium oxide is mixed with siliconoxide, organic indium, organic tin, indium oxide containing tungstenoxide, indium zinc oxide containing tungsten oxide, indium oxidecontaining titanium oxide, indium tin oxide containing titanium oxide,or metal such as tungsten (W), molybdenum (Mo), zirconium (Zr), hafnium(Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), cobalt(Co), nickel (Ni), titanium (Ti), platinum (Pt), aluminum (Al), copper(Cu), or silver (Ag), or an alloy or a metal nitride thereof.

A conductive composition including a conductive high molecular compound(also referred to as a conductive polymer) can be used for the pixelelectrode layer 674. In the case where a thin film is formed using theconductive composition as the pixel electrode, it is preferable thatsheet resistance of the thin film be 10000 Ω/sq. or less. In the casewhere a thin film is formed as a pixel electrode layer having alight-transmitting property, it is preferable that light transmittanceat a wavelength of 550 nm be 70% or more, and resistivity of theconductive high molecular compound included be 0.1 Ω·cm or lower.

As the conductive high molecular compound, a so-called π electronconjugated conductive high molecular compound can be used. For example,polyaniline and a derivative thereof, polypyrrole and a derivativethereof, polythiophene and a derivative thereof, or a copolymer of thosematerials can be given.

Specific examples of the conjugated conductive high molecular compoundare given below: polypyrrole, poly(3-methylpyrrole),poly(3-butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole),poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole),poly(3-hydroxypyrrole), poly(3-methyl-4-hydroxypyrrole),poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-octoxypyrrole),poly(3-carboxylpyrrole), poly(3-methyl-4-carboxylpyrrole),polyN-methylpyrrole, polythiophene, poly(3-methylthiophene),poly(3-butylthiophene), poly(3-octylthiophene), poly(3-decylthiophene),poly(3-dodecylthiophene), poly(3-methoxythiophene),poly(3-ethoxythiophene), poly(3-octoxythiophene),poly(3-carboxylthiophene), poly(3-methyl-4-carboxylthiophene),poly(3,4-ethylenedioxythiophene), polyaniline, poly(2-methylaniline),poly(2-octylaniline), poly(2-isobutylaniline), poly(3-isobutylaniline),poly(2-anilinesulfonic acid), and poly(3-anilinesulfonic acid).

The above conductive high molecular compound may be used alone, or anorganic resin may be added thereto in order to adjust the characteristicof the films.

As for an organic resin, as long as a resin is compatible to aconductive high molecular compound or a resin can be mixed and dispersedinto a conductive high molecular compound, a thermosetting resin, athermoplastic resin, or a photocurable resin may be used. Specificexamples of the organic resin are given below: a polyester-based resinsuch as polyethylene terephthalate, polybutylene terephthalate, orpolyethylene naphthalate; a polyimide-based resin such as polyimide orpolyamide imide; a polyamide resin such as polyamide 6, polyamide 66,polyamide 12, or polyamide 11; a fluorine resin such as poly(vinylidenefluoride), polyvinyl fluoride, polytetrafluoroethylene, ethylenetetrafluoroethylene copolymer, or polychlorotrifluoroethylene; a vinylresin such as polyvinyl alcohol, polyvinyl ether, polyvinyl butyral,polyvinyl acetate, or polyvinyl chloride; an epoxy resin; a xyleneresin; an aramid resin; a polyurethane-based resin; a polyurea-basedresin, a melamine resin; a phenol-based resin; polyether; anacrylic-based resin, or a copolymer of any of those resins.

Furthermore, by doping a conductive composition with acceptor typedopant or donor type dopant, an oxidation-reduction potential of aconjugated electron of a conjugated conductive high molecular compoundis changed; therefore, electrical conductivity may be adjusted.

As the acceptor type dopant, a halogen compound, a Lewis acid, aprotonic acid, an organic cyano compound, an organic metal compound, orthe like can be used. Examples of a halogen compound are chlorine,bromine, iodine, iodine chloride, iodine bromide, and iodine fluoride.Examples of a Lewis acid are phosphorus pentafluoride, arsenicpentafluoride, antimony pentafluoride, boron trifluoride, borontrichloride, and boron tribromide. Examples of a protonic acid are aninorganic acid such as a hydrochloric acid, a sulfuric acid, a nitricacid, a phosphoric acid, a fluoric acid, a hydrofluoric acid, and aperchloric acid, and an organic acid such as an organic carboxylic acidand an organic sulfonic acid. As the organic carboxylic acid and theorganic sulfonic acid, an organic carboxylic acid compound and anorganic sulfonic acid compound can be used. As the organic cyanocompound, a compound having two or more cyano groups in a conjugatedbonding, for example, tetracyanoethylene, tetracyanoethylene oxide,tetracyanobenzene, tetracyanoquinodimethane, andtetracyanoazanaphthalene are given.

As the donor type dopant, alkali metal, alkaline-earth metal, aquaternary amine compound, or the like can be used.

The aforementioned conductive composition is dissolved in water or anorganic solvent (e.g., an alcohol-based solvent, a ketone-based solvent,an ester-based solvent, a hydrocarbon-based solvent, an aromatic-basedsolvent) and a thin film which serves as the pixel electrode layer 674can be formed by a wet process such as an application method, a coatingmethod, a droplet discharge method (also referred to as an ink-jetmethod), a printing method, or the like.

Subsequently, an insulating layer 902 referred to as an alignment filmis formed to cover the pixel electrode layer 674 and the insulating film672 (see FIG. 9B). The insulating layer 902 can be formed by a screenprinting method or an offset printing method. FIGS. 9A and 9B are aplane view and a cross sectional view of a semiconductor device. FIG. 9Ais a plane view of the semiconductor device, and FIG. 9B is a crosssectional view taken along a line C-D of FIG. 9A. The semiconductordevice includes an external terminal connection region 676, a sealingregion 678, a peripheral driver circuit region 680, and a pixel region690.

After forming the insulating layer 902, rubbing treatment is performed.An insulating layer 906 which serves as an alignment film can be formedin a similar manner to the insulating layer 902.

Then, a counter substrate 900 is attached to the substrate 600 havingthe insulating surface with a sealing material 914 and a spacer 916interposed therebetween, and a liquid crystal layer 904 is provided in agap therebetween. The counter substrate 900 is provided with theinsulating layer 906 serving as an alignment film, a conductive layer908 serving as a counter electrode, a colored layer 910 serving as acolor filter, a polarizer 912 (also referred to as a polarizing plate),and the like. Note that the substrate 600 having the insulating surfaceis provided with a polarizer 918 (polarizing plate); however, thepresent invention is not limited thereto. For example, in a reflectiveliquid crystal display device, a polarizer may be provided for either acounter substrate or a substrate.

Subsequently, an FPC 924 is connected to a terminal electrode layer 920that is electrically connected to the pixel region, with an anisotropicconductive layer 922 interposed therebetween. The FPC 924 has a functionof transmitting a signal from the external. The liquid crystal displaydevice can be manufactured by the above-described process.

In the present invention, by performing a plasma treatment to the singlecrystal semiconductor layer 606, a defect in an interface between thebonding layer 604 and the single crystal semiconductor layer 606 isreduced. As a result, a semiconductor element having excellentcharacteristics can be manufactured in each of a pixel region and aperipheral circuit region. Specifically, in the pixel region and theperipheral circuit region, a transistor of which fluctuation in athreshold voltage is small, mobility is high, and subthreshold swing(V_(g) which is necessary to increase I_(d) by an order of magnitude inI_(d)−V_(g) curve) is small can be manufactured. Further, a highlyreliable transistor can be manufactured.

By using the transistor having excellent characteristics as described inthis embodiment mode, sufficient high-speed operation is realized in aperipheral circuit region and an accurate gray scale display withhigh-speed operation is realized in a pixel region. In other words, asemiconductor device having high image quality and excellent movingimage characteristics can be provided. Moreover, since it is notnecessary to provide an IC chip externally, thickness and an area of aframe portion of a semiconductor device can be reduced, and asemiconductor device which effectively utilizes a display area can beprovided at low cost.

Note that a method for manufacturing a liquid crystal display device isdescribed in this embodiment mode; however, the present invention is notlimited to this. This embodiment mode can be combined with EmbodimentMode 1 and 2 as appropriate.

Embodiment Mode 4

In this embodiment mode, a semiconductor device (electroluminescencedisplay device) having a light emitting element according to the presentinvention is described. Embodiment Mode 3 can be referred to for themethod for manufacturing a transistor used in a peripheral circuitregion, a pixel region, and the like; therefore, detailed description isomitted.

In a semiconductor device having a light emitting element, any manner ofbottom emission, top emission, or dual emission is used. In thisembodiment mode, a semiconductor device using bottom emission isdescribed with reference to FIGS. 10A and 10B; however, the presentinvention is not limited to this.

The semiconductor device in FIGS. 10A and 10B emits light to the lowerside (in the direction of an arrow shown in the drawing). FIG. 10A is aplan view showing the semiconductor device, and FIG. 10B is across-sectional view taken along a line E-F of FIG. 10A. Thesemiconductor device of FIGS. 10A and 10B includes an external terminalconnection region 1030, a sealing region 1032, a driver circuit region1034, and a pixel region 1036.

The semiconductor device shown in FIGS. 10A and 10B includes an elementsubstrate 1000, an insulating film 1002, a thin film transistor 1050, athin film transistor 1052, a thin film transistor 1054, a thin filmtransistor 1056, a light emitting element 1060, an insulating layer1068, a filling material 1070, a sealing material 1072, a wiring layer1074, a terminal electrode layer 1076, an anisotropic conductive layer1078, an FPC 1080, and a sealing substrate 1090. Note that the lightemitting element 1060 includes a first electrode layer 1062, a lightemitting layer 1064, and a second electrode layer 1066.

As the first electrode layer 1062, a conductive material having alight-transmitting property is used so as to transmit light emitted fromthe light emitting layer 1064. On the other hand, as the secondelectrode layer 1066, a conductive material which can reflect lightemitted from the light emitting layer 1064 is used.

As the first electrode layer 1062, indium oxide containing tungstenoxide, indium zinc oxide containing tungsten oxide, indium oxidecontaining titanium oxide, indium tin oxide containing titanium oxide,or the like can be used. Of course, indium tin oxide (ITO), indium zincoxide (IZO), indium tin oxide added with silicon oxide (ITSO), or thelike can be used.

As the first electrode layer 1062, a conductive composition including aconductive high molecular compound (also referred to as a conductivepolymer) can be used. Embodiment Mode 3 can be referred to for thedetail; therefore, description is omitted here.

As the second electrode layer 1066, a conductive film formed oftitanium, tungsten, nickel, gold, platinum, silver, copper, tantalum,molybdenum, aluminum, magnesium, calcium, lithium, or an alloy thereof,or the like may be used. It is preferable to use a substance having highreflectivity in a visible light range, and an aluminum film is used inthis embodiment mode.

In the case of applying each manner of top emission and dual emission,an electrode layer may be appropriately designed. Specifically, in thecase of applying the top emission, the first electrode layer 1062 isformed using a reflective material and the second electrode layer 1066is formed using a light-transmitting material. In the case of applyingdual emission, the first electrode layer 1062 and the second electrodelayer 1066 are formed using a light-transmitting material. Note that inthe case of applying bottom emission or top emission, a structure may bethat one electrode layer is formed using a light-transmitting material,and the other electrode layer is formed to have a stacked-layerstructure using a light-transmitting material and a light reflectivematerial. A material which can be used for forming the electrode layeris the same as the case of applying the bottom emission, description isomitted.

Further, even if a material such as a metal film which does not have alight-transmitting property is used, light can be transmitted by formingthe layer to be thin (about 5 to 30 nm). Accordingly, an electrode layerwhich can transmit light can be manufactured by using theabove-mentioned light reflective material.

A color filter (colored layer) may be formed on the sealing substrate1090. The color filter (colored layer) can be formed by an evaporationmethod or a droplet discharge method. Furthermore, a color conversionlayer may be used.

In the present invention, by performing plasma treatment to a singlecrystal semiconductor layer, a defect in an interface between thebonding layer and the single crystal semiconductor layer is reduced. Asa result, a semiconductor element having excellent characteristics canbe manufactured in each of a pixel region and a peripheral circuitregion. Specifically, in the pixel region and the peripheral circuitregion, a transistor of which fluctuation in a threshold voltage issmall, mobility is high, and subthreshold swing (V_(g) which isnecessary to increase I_(d) by an order of magnitude in I_(d)−V_(g)curve) is small can be manufactured. Further, a highly reliabletransistor can be manufactured.

By using a transistor having excellent characteristics as described inthis embodiment mode, sufficient high-speed operation is realized in aperipheral circuit region and an accurate gray scale display withhigh-speed operation is realized in a pixel region. In other words, asemiconductor device having high image quality and excellent movingimage characteristics can be provided. Moreover, since it is notnecessary to provide an IC chip externally, thickness and an area of aframe portion of a semiconductor device can be reduced, and asemiconductor device which effectively utilizes a display area can beprovided at low cost.

The embodiment mode is described using an electroluminescence displaydevice; however, the present invention is not limited to this. Thisembodiment mode can be combined with Embodiment Modes 1 to 3 asappropriate.

Embodiment Mode 5

In this embodiment mode, another example of a semiconductor deviceaccording to the present invention is described with reference to FIG.11 and FIG. 12. In this embodiment mode, a microprocessor and anelectronic tag are given for the description; however the semiconductordevice of the invention is not limited to these.

FIG. 11 shows an example of a microprocessor of the present invention. Amicroprocessor 1100 in FIG. 11 is manufactured using a semiconductorsubstrate of the invention. This microprocessor 1100 has an arithmeticlogic unit (also referred to as ALU) 1101, an ALU controller 1102, aninstruction decoder 1103, an interrupt controller 1104, a timingcontroller 1105, a register 1106, a register controller 1107, a businterface (Bus I/F) 1108, a read only memory (ROM) 1109, and a memoryinterface (ROM I/F) 1110.

An instruction inputted to the microprocessor 1100 through the businterface 1108 is inputted to the instruction decoder 1103 and decoded.Then, the instruction is inputted to the ALU controller 1102, theinterrupt controller 1104, the register controller 1107, and the timingcontroller 1105. The ALU controller 1102, the interrupt controller 1104,the register controller 1107, and the timing controller 1105 performvarious controls based on the decoded instruction. Specifically, the ALUcontroller 1102 generates a signal for controlling the operation of thearithmetic logic unit 1101. The interrupt controller 1104 determines aninterrupt request from an external input/output device or a peripheralcircuit based on its priority or the like, and processes the requestwhile a program of the microprocessor 1100 is executed. The registercontroller 1107 generates an address of the register 1106, andreads/writes data from/to the register 1106 in accordance with the stateof the microprocessor 1100. The timing controller 1105 generates signalsfor controlling timing of driving of the arithmetic logic unit 1101, theALU controller 1102, the instruction decoder 1103, the interruptcontroller 1104, and the register controller 1107. For example, thetiming controller 1105 is provided with an internal clock generator forgenerating an internal clock signal CLK2 based on a reference clocksignal CLK1, and supplies the clock signal CLK2 to each of theabove-mentioned circuits. It is to be noted that the microprocessor 1100illustrated in FIG. 11 is just an example of the simplified structure,and practical microprocessors have various structures depending onusage.

In the microprocessor 1100 of the present invention, an integratedcircuit is formed using a single crystal semiconductor layer in which acrystal orientation is uniform which is bonded to a glass substrate;therefore, high processing speed and low power consumption can berealized. Further, in the microprocessor 1100 manufactured using asemiconductor substrate of the invention, plasma treatment is performedto the single crystal semiconductor layer and a defect in an interfacebetween a bonding layer and the single crystal semiconductor layer isreduced. Accordingly, a characteristic of a semiconductor element isimproved, and a microprocessor with very high performance and highreliability can be provided.

Next, an example of a semiconductor device having an arithmeticfunction, which is capable of transmitting and receiving data withoutcontact, is described with reference to FIG. 12. FIG. 12 is an exampleof a wireless tag which operates by transmitting and receiving signalto/from an external device by wireless communication. Note that thewireless tag of the invention has a central processing unit (CPU) in itsinside, and is a so-called small computer. This wireless tag 1200 has ananalog circuit portion 1201 and a digital circuit portion 1202. Theanalog circuit portion 1201 includes a resonant circuit 1203 having aresonant capacitor, a rectifier circuit 1204, a constant voltage circuit1205, a reset circuit 1206, an oscillator circuit 1207, a demodulationcircuit 1208, and a modulation circuit 1209. The digital circuit portion1202 includes an RF interface 1210, a control register 1211, a clockcontroller 1212, an interface 1213, a central processing unit (CPU)1214, a random access memory (RAM) 1215, and a read only memory (ROM)1216.

The operation of the wireless tag 1200 having such a structure isroughly described below. A signal received at an antenna 1217 causesinduced electromotive force at the resonant circuit 1203. The inducedelectromotive force is stored in a capacitor portion 1218 via therectifier circuit 1204. The capacitor portion 1218 is preferably formedusing a capacitor such as a ceramic capacitor or an electric doublelayer capacitor. The capacitor portion 1218 may be formed over the samesubstrate as the wireless tag 1200 or may be attached as anothercomponent to a substrate having an insulating surface that partiallyconstitutes the wireless tag 1200.

The reset circuit 1206 generates a signal that resets the digitalcircuit portion 1202 to be initialized. For example, the reset circuit1206 generates, as a reset signal, a signal that rises with delay afterincrease in the power supply voltage. The oscillation circuit 1207changes the frequency and the duty ratio of a clock signal in accordancewith a control signal generated by the constant voltage circuit 1205.The demodulation circuit 1208 having a low pass filter, for example,binarizes changes in amplitude of reception signals of an amplitudeshift keying (ASK) system. The modulation circuit 1209 changes theamplitude of transmission signals of an amplitude shift keying (ASK)system to be transmitted. The modulation circuit 1209 changes theresonance point of the resonant circuit 1203, thereby changing theamplitude of communication signals. The clock controller 1212 generatesa control signal for changing the frequency and the duty ratio of theclock signal in accordance with the power supply voltage or currentconsumption in the central processing unit 1214. The power supplyvoltage is monitored by a power supply control circuit 1219.

A signal that is inputted to the wireless tag 1200 from the antenna 1217is demodulated by the demodulation circuit 1208, and then divided into acontrol command, data, and the like by the RF interface 1210. Thecontrol command is stored in the control register 1211. The controlcommand includes, reading of data stored in the read only memory 1216,writing of data to the random access memory 1215, an arithmeticinstruction to the central processing unit 1214, and the like. Thecentral processing unit 1214 accesses the read only memory 1216, therandom access memory 1215, and the control register 1211 via theinterface 1213. The interface 1213 has a function of generating anaccess signal for any one of the read only memory 1216, the randomaccess memory 1215, and the control register 1211 based on an addressrequested by the central processing unit 1214.

As an arithmetic method of the central processing unit 1214, a methodmay be employed in which the read only memory 1216 stores an OS(operating system) and a reading program is executed at the time ofstarting operation. Alternatively, a method may be employed in which anarithmetic circuit is formed and an arithmetic process is conductedusing hardware. In a method in which both hardware and software areused, a method can be used in which a part of process is conducted in adedicated arithmetic circuit and the other part of the arithmeticprocess is conducted by the central processing unit 1214 using aprogram.

In the wireless tag 1200 of the present invention, an integrated circuitis formed using a single crystal semiconductor layer in which a crystalorientation is uniform which is bonded to a glass substrate; therefore,high processing speed and low power consumption can be realized.Further, in the wireless tag 1200 manufactured using a semiconductorsubstrate of the invention, plasma treatment is performed to the singlecrystal semiconductor layer and a defect in an interface between abonding layer and the single crystal semiconductor layer is reduced.Accordingly, a characteristic of a semiconductor element is improved,and a microprocessor with very high performance and high reliability canbe provided.

This embodiment mode can be combined with Embodiment Modes 1 to 4 asappropriate.

Embodiment Mode 6

In this embodiment mode, electronic devices in which a semiconductordevice of the present invention, specifically, a display device is usedwill be described with reference to FIGS. 13A to 13H.

Examples of the electronic devices manufactured using the semiconductordevice of the invention are as follows: video cameras; digital cameras;goggles-type displays (head-mounted displays); navigation systems; audioplayback devices (car audio components and the like); computers; gamemachines; portable information terminals (mobile computers, cellularphones, portable game machines, electronic book readers, and the like);image playback devices provided with storage media (specifically,devices that can play storage media such as digital versatile discs(DVDs) or the like and that are equipped with a display device by whichthe images can be displayed); and the like.

FIG. 13A is a diagram of a television set or a monitor of a personalcomputer. The television set or the monitor of the personal computerincludes a chassis 1301, a support stand 1302, a display 1303, speakers1304, video input terminals 1305, and the like. The semiconductor deviceof the present invention is used in the display 1303. By the presentinvention, a television set or a monitor of a personal computer withexcellent image quality can be provided at low cost.

FIG. 13B is a diagram of a digital camera. On the front side part of amain body 1311, an image receiver 1313 is provided, and on the top sidepart of the main body 1311, a shutter button 1316 is provided.Furthermore, on the back side part of the main body 1311, a display1312, operation keys 1314, and an external connection port 1315 areprovided. The semiconductor device of the present invention is used inthe display 1312. According to the present invention, a digital camerawith excellent image quality can be provided at low cost.

FIG. 13C is a diagram of a notebook personal computer. In a main body1321, a keyboard 1324, an external connection port 1325, and a pointingdevice 1326 are provided. Furthermore, a chassis 1322 that has a display1323 is attached to the main body 1321. The semiconductor device of thepresent invention is used in the display 1323. According to the presentinvention, a notebook personal computer with excellent image quality canbe provided at low cost.

FIG. 13D is a diagram of a mobile computer that includes a main body1331, a display 1332, a switch 1333, operation keys 1334, an infraredport 1335, and the like. Furthermore, an active matrix display device isprovided in the display 1332. The semiconductor device of the presentinvention is used in the display 1332. According to the presentinvention, a mobile computer with excellent image quality can beprovided at low cost.

FIG. 13E is a diagram of an image playback device. In a main body 1341,a display B 1344, a storage media reader 1345, and operation keys 1346are provided. Furthermore, a chassis 1342 that has speakers 1347 and adisplay A 1343 is attached to the main body 1341. The semiconductordevice of the present invention is used in each of the display A 1343and the display B 1344. According to the present invention, an imageplayback device with excellent image quality can be provided at lowcost.

FIG. 13F is a diagram of an electronic book reader. In a main body 1351,operation keys 1353 are provided. Furthermore, a plurality of displays1352 is attached to the main body 1351. The semiconductor device of thepresent invention is used in each of the displays 1352. According to thepresent invention, an electronic book reader with excellent imagequality can be provided at low cost.

FIG. 13G is a diagram of a video camera. In a main body 1361, anexternal connection port 1364, a remote control receiver 1365, an imagereceiver 1366, a battery 1367, an audio input 1368, and operation keys1369 are provided. Furthermore, a chassis 1363 that has a display 1362is attached to the main body 1361. The semiconductor device of thepresent invention is used in the display 1362. According to the presentinvention, a video camera with excellent image quality can be providedat low cost.

FIG. 13H is a diagram of a cellular phone that includes a main body1371, a chassis 1372, a display 1373, an audio input 1374, an audiooutput 1375, operation keys 1376, an external connection port 1377, anantenna 1378, and the like. The semiconductor device of the presentinvention is used in the display 1373. According to the presentinvention, a cellular phone with excellent image quality can be providedat low cost.

As described above, the range of application of the present invention isextremely wide, and the present invention can be used in electronicdevices of all fields. It is to be noted that the present embodimentmode can be used in combination with Embodiment Mode 1 throughEmbodiment Mode 5, as appropriate.

Embodiment Mode 7

In this embodiment mode, applications of a semiconductor device of thepresent invention, specifically, a wireless tag is described withreference to FIGS. 14A to 14F.

A semiconductor device functioning as a wireless tag can be formedaccording to the present invention. The wireless tag can be used in awide variety of application, and may be used by being mounted on objectssuch as bills, coins, securities, bearer bonds, certificates (driver'slicenses, resident cards, and the like, see FIG. 14A), containers forwrapping objects (wrapping paper, bottles, and the like, see FIG. 14C),recording media (DVD software, video tapes, and the like, see FIG. 14B),vehicles (bicycles and the like, see FIG. 14D), personal belongings(bags, glasses, and the like), foods, plants, clothes, lifestyle goods,and products such as electronic devices, or shipping tags of baggage(see FIGS. 14E and 14F). Note that the wireless tag is indicated byreference numeral 1400 in each of FIGS. 14A to 14F.

Note that the electronic device indicates a liquid crystal displaydevice, an EL display device, a television unit (also simply referred toas a TV, a TV receiver, or a television receiver), a cellular phone, andthe objects shown in Embodiment Mode 5, for example. In addition, theabove-described semiconductor device can be used for animals, humanbodies, or the like.

The wireless tag is attached to a surface of an object, or embedded tobe fixed on an object. For example, the wireless tag may be incorporatedin paper of a book, or an organic resin of a container for wrapping anobject to be fixed on each object. By providing an RFID tag in bills,coins, securities, bearer bonds, certificates, and the like, forgery canbe prevented. Further, by providing an RFID tag in containers forwrapping objects, recording media, personal belongings, foods, clothes,lifestyle goods, electronic devices, and the like, inspection systems,rental systems and the like can be performed more efficiently. Thewireless tag which can be manufactured according to the presentinvention has high performance and reliability, and can be applied tovarious objects.

When a wireless tag that can be formed according to the presentinvention is applied to a management system or a distribution system ofarticles, the system can have high functionality. For example,information which is recorded in a wireless tag provided in a tag isread by a reader/writer provided near a conveyor belt, then informationabout a distribution process or a delivery destination is read out, andinspection of merchandise or distribution of goods can be easily carriedout.

As described, the present invention can be widely applied to and used invarious objects. This embodiment mode can be combined with EmbodimentModes 1 to 6 as appropriate.

Embodiment 1

In this embodiment, details such as manufacturing condition of asemiconductor substrate of the present invention will be described withreference to FIGS. 15A to 15D and FIG. 16A to 16C.

First, a single crystal silicon substrate 1500 is prepared. Here, thesubstrate 1500 has a thickness of about 700 μm. Next, a siliconoxynitride film 1502 functioning as a protective layer is formed overthe single crystal silicon substrate 1500 with a thickness of about 150nm (see FIG. 15A). In this embodiment, the silicon oxynitride film isformed by a chemical vapor deposition (CVD) method.

Then, the surface of the single crystal silicon substrate 1500 isirradiated with ions through the silicon oxynitride film 1502 tointroduce hydrogen ions (H⁺, H₂ ⁺, H₃ ⁺, and the like) in a given depth,thereby forming a damaged region 1504 and a single crystal silicon layer1506 (see FIG. 15B). The single crystal silicon layer 1506 manufacturedby ion irradiation has a thickness of about 90 nm. The ion irradiationin this embodiment is conducted using an H₂ gas as a material gas withan acceleration voltage of 40 kV at a dose of 2.0×10¹⁶ ions/cm².

After forming the damaged region 1504, the silicon oxynitride film 1502is removed, and plasma treatment is performed to the surface of thesingle crystal silicon layer 1506 (see FIG. 15C). The silicon oxynitridefilm 1502 is removed by wet etching using buffered hydrogen fluoride(BHF). The plasma treatment is performed under a mixed atmosphere ofoxygen (O₂) and hydrogen (H₂). More specifically, plasma is generated bykeeping pressure to be 40 Pa and using O₂ and H₂ at flow rates of 100sccm and 100 sccm, and applying power of 100 W and 27.12 MHz. Note thatthe interval between the electrodes is about 20 mm.

A silicon oxynitride film 1508 is formed after the plasma treatment. Inthis embodiment, the silicon oxynitride film 1508 is formed by keepingpressure to be 40 Pa using SiH₄ and N₂O at flow rates of 4 sccm and 800sccm, and applying power of 50 W and 27.12 Mz. Then, a silicon nitrideoxide film 1510 is formed over the silicon oxynitride film 1508 (seeFIG. 15D). Note that the silicon oxynitride film 1508 and the siliconnitride oxide film 1510 are formed at a temperature of 400° C. or less.Further, the silicon oxynitride film 1508 has a thickness of about 100nm and the silicon nitride oxide film 1510 has a thickness of about 50nm.

Subsequently, a silicon oxide film 1512 functioning as a bonding layeris formed over the silicon nitride oxide film 1510 (see FIG. 16A). Inthis embodiment, the silicon oxide film 1512 is formed using tetraethylortho silicate (TEOS, Si(OC₂H₅)₄) by a chemical vapor deposition (CVD)method. The film thickness of the silicon oxide film 1512 is about 50nm.

Then, the single crystal silicon substrate 1500 and a glass substrate1514 are disposed into contact with each other with the silicon oxidefilm 1512 interposed therebetween (see FIG. 16B). The glass substrate1514 and the silicon oxide film 1512 are disposed in contact with eachother and pressure is applied thereto; therefore, a strong bond can beformed.

Next, heat treatment is performed, and the single crystal silicon layer1506 is separated from the single crystal silicon substrate 1500 usingthe damaged region 1504 as a separation surface (see FIG. 16C). In thisembodiment, the single crystal silicon layer 1506 is separated from thesingle crystal silicon substrate 1500 by the heat treatment at 600° C.for two hours.

According to the above steps, the semiconductor substrate in which thesilicon oxide film 1512 functioning as the bonding layer, the siliconnitride oxide film 1510, the silicon onynitride film 1508, and thesingle crystal silicon layer 1506 are stacked over the glass substrate1514 is formed.

Note that this embodiment is just one example, and the present inventionis not limited to this. And the condition and the like of thisembodiment can be properly combined with any of Embodiment Modes 1 to 7.

This application is based on Japanese Patent Application serial no.2007-165494 filed with Japan Patent Office on Jun. 22, 2007, the entirecontents of which are hereby incorporated by reference.

1. A method for manufacturing a semiconductor substrate comprising thesteps of: forming a damaged region at a given depth from a surface of asingle crystal semiconductor substrate; performing a plasma treatment tothe surface of the single crystal semiconductor substrate after formingthe damaged region; forming an insulating layer over the surface of thesingle crystal semiconductor substrate to which the plasma treatment isperformed; bonding a second substrate having an insulating surface tothe single crystal semiconductor substrate with at least the insulatinglayer interposed between the second substrate and the single crystalsemiconductor substrate; and performing a heat treatment to the singlecrystal semiconductor substrate to separate the single crystalsemiconductor substrate in the damaged region and to form a singlecrystal semiconductor layer over the second substrate.
 2. The method formanufacturing a semiconductor substrate according to claim 1, whereinthe insulating layer is formed by a chemical vapor deposition methodusing an organic silane gas.
 3. The method for manufacturing asemiconductor substrate according to claim 1 further comprising thesteps of: forming a protective film over the surface of the singlecrystal semiconductor substrate before forming the damaged region; andremoving the protective film after forming the damaged region.
 4. Themethod for manufacturing a semiconductor substrate according to claim 1,wherein the plasma treatment is performed under conditions of anelectron density of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electrontemperature of 0.2 eV to 2.0 eV.
 5. The method for manufacturing asemiconductor substrate according to claim 1, wherein the plasmatreatment is performed under a hydrogen atmosphere, an oxygenatmosphere, or a mixed atmosphere of hydrogen and oxygen.
 6. A methodfor manufacturing a semiconductor substrate comprising the steps of:forming a damaged region at a given depth from a surface of a singlecrystal semiconductor substrate; performing a plasma treatment to thesurface of the single crystal semiconductor substrate after forming thedamaged region; forming a first insulating layer over the surface of thesingle crystal semiconductor substrate to which the plasma treatment isperformed; forming a second insulating layer over and in contact withthe first insulating layer; bonding a second substrate having aninsulating surface to the single crystal semiconductor substrate with atleast the first insulating layer and the second insulating layerinterposed between the second substrate and the single crystalsemiconductor substrate; and performing a heat treatment to the singlecrystal semiconductor substrate to separate the single crystalsemiconductor substrate in the damaged region and to form a singlecrystal semiconductor layer over the second substrate.
 7. The method formanufacturing a semiconductor substrate according to claim 6, whereinthe first insulating layer is formed to have a stacked-layer structure.8. The method for manufacturing a semiconductor substrate according toclaim 6, wherein the first insulating layer is formed to have astacked-layer structure of a silicon oxynitride layer and a siliconnitride oxide layer, and the silicon oxynitride layer is formed incontact with the single crystal semiconductor substrate.
 9. The methodfor manufacturing a semiconductor substrate according to claim 6,wherein the second insulating layer is formed by a chemical vapordeposition method using an organic silane gas.
 10. The method formanufacturing a semiconductor substrate according to claim 6 furthercomprising the steps of: forming a protective film over the surface ofthe single crystal semiconductor substrate before forming the damagedregion; and removing the protective film after forming the damagedregion.
 11. The method for manufacturing a semiconductor substrateaccording to claim 6, wherein the plasma treatment is performed underconditions of an electron density of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and anelectron temperature of 0.2 eV to 2.0 eV.
 12. The method formanufacturing a semiconductor substrate according to claim 6, whereinthe plasma treatment is performed under a hydrogen atmosphere, an oxygenatmosphere, or a mixed atmosphere of hydrogen and oxygen.